What is polyurethane spray foam?
In private residential construction practice, polyurethane foam is increasingly used.
However, everyone is probably familiar with this material since childhood: foam rubber – which is also a type of polyurethane foam – is used to make sponges and also as filler for soft toys or children,s furniture.
Of course, other types of polyurethane are also used to insulate building structures, but the basic chemical composition and the principles for obtaining the material remain the same. A characteristic of all polyurethane foams is a high gas content, which amounts to 90% of the total volume of the frozen mass.
Polyurethane foam therefore refers to a porous air-filled polymer based on polyurethane components. Depending on the specific components used, the inputs can be elastic, elastic structures (again foam rubber) or rigid structures, mainly used for thermal insulation measures.
When insulating certain building structures, ready-made insulating polyurethane foam parts can be used, such as panels, blocks, semi-cylinders (tube shells), etc. However, the greatest need is for compositions that are applied in liquid form to insulating surfaces (or poured into cavities) but have the ability to self-foam and rapidly polymerize and harden. Therefore, in essence, the preparation of the required composition takes place directly at the insulation work site.
For large-scale work, use a two-component composition. Typically, modern technology involves using polyols as component "A" and polyisocyanates as "B".
When these components are mixed in the presence of a small amount of water, a polymer synthesis reaction occurs and gas (in this case, carbon dioxide) is actively released, resulting in a foamy, porous, rigid structure. This polyurethane foam has a closed-cell structure-the vast majority of the air cells are completely isolated from adjacent cells.
All other things being equal, the thermal conductivity of carbon dioxide filling a cell is significantly lower than that of air by about one-third (0.016 W/m x℃ vs. 0.026 W/m x℃), which is Another significant advantage of closed-cell polyurethane foam is its ability as an effective thermal insulator.
Some professional, high-quality systems use Freon as a blowing agent.